Apparatus for oil well paraffin control



Sept. 21, 1965 E. L. MITCHELL APPARATUS FOR OIL WELL PARAFFIN CONTROL Filed Aug. 26, 1960 4 Sheets-Sheet 1 TANK TANK

INVENTOR.

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Sept. 21, 1965 E. MITCHELL 3,207,219

APPARATUS FOR OIL WELL PARAFFIN CONTROL Filed Aug. 26, 1960 4 Sheets-Sheet 2 FIG. 3.

INVEN TOR. E0648 4. M/TCA ELL P 1965 E. L. MITCHELL 3,207,219

APPARATUS FOR OIL, WELL PARAFFIN CONTROL Filed Aug. 26. 1960 4 Sheets-Sheet 5 IN VEN TOR.

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APPARATUS FOR OIL WELL PARAFFIN CONTROL Filed Aug. 26, 19 60 4 Sheets-Sheet 4 FIG. 10.

INVENTOR.

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United States Patent 3,207,219 APPARATUS FOR OIL WELL PARAFFIN CONTROL Edgar L. Mitchell, 1209 Schofield Lane, Farmington, N. Mex. Filed Aug. 26, 1960, Ser. No. 52,216 5 Claims. (Cl. 166-57) This invention relates to novel apparatus for oil well paraffin control by controlled circulation :of heated fluid in the annulus between the tubing and the casing of wells.

The primary object .of the invention is the provision of more eflective, more eflicient, and more reliable means for controlling the formation of paraffin in the tubing of Wells, of either the pumping or flowing types, without interfering with the production of the well itself.

In certain oil fields paraflin formation on the Wall of Well tubing and a viscous non-flowing condition of the oil is a constant problem, as in cold climate areas, while in some other fields paraflin formation and viscous oil condition is a varying problem, due to varying well conditions and to variations in temperature, as in wintertime. The present invention is elfective for reducing and eliminating these problems, and is sufliciently versatile and controllable to be adaptable to all of such problems.

Another object of the invention is the provision of means of the character indicated above which are substantially more economical than presently practiced means, the said means including fluid circulating apparatus which .is readily transportable, over rough terrain, to the sites of wells to be treated, so as to eliminate or reduce the expense and trouble of permanent individual installations at individual wells, and so as to make it physically and economically feasible to reach and treat one or more wells simultaneously, in areas not otherwise reachable on a feasible basis, and areas not traversable by trucks loaded with apparatus.

A further object of the invention is the provision of means of the character indicated above which involves blocking the annulus between the tubing and the casing of a well, after a temperautre survey of the well to determine the depth of the cold zone, at the lower end of the cold araflin depositing cold zone, and then continuously circulating, in the zone thus created between the block and the head of the well, freeze proof, non-evaporative fluid, at a high enough automatically controlled temperature, to heat the wall of the Well tubing so as to melt paraflin present thereon and reduce or eliminate further deposition of paraflin thereon, while at the same time beating the oil and Well fluid rising to the zone so as to eliminate slow flow of viscous oil to the head of the well, which transit through the cold zone otherwise produces.

A still further object of the invention is the provision of means of the character indicated above which involves means for testing or sampling the circulation fluid after passage through the heated cold zone, so as to make available, whenever wanted, information of the condition of the well, such as leakage or other material deterioration of the packer or packers of the Well string and of the blocking means defining the bottom of the circulation zone.

Yet another object of the invention is the provision of means of the character indicated above, wherein the fluid in circulating zone is isolated from and out of contact with the working fluid of the well, so that there is no 3,207,219 Patented Sept. 21, 1965 loss of circulating fluid in the well, and no mixture of or contamination of either the circulating fluid or the well fluid, including the oil, as normally occurs.

Still another object of the invention is to provide means of the character indicated above wherein the blocking of a well annulus to produce a circulating zone is accomplished by the use of a combination circulation stop and swab, which is connected between two adjacent well tubing sections, and above a acker in the case of a working well, the combination device serving, while in place to effectively block flow of circulation fluid downwardly therethrough to the well annulus below the device, and serving, when drawn upwardly in the well casing, as a swab for pushing out of the well the circulating fluid present in the annulus above the device.

A yet further object of the invention is the provision of a combination circulation stop and swab of the character indicated above, which is provided with normally closed relief valve means which permits well fluid in the annulus below the device to pass upwardly through the device should excessive upward pressures develop thereon; the arrangement of the device relative to the tubing providing for killing of the well through the tubing, and other related operations, by pumping mud down through the tubing and up through the relief valve means.

Another object of the invention is the provision of a combination of the character indicated above which has vertical passage means extending therethrough to provide communication between the well annulus, above and below the combination, and upwardly opening check valve means in the passage means and normally closing the same, whereby development of pressure below the combination, greater than the circulation pressure in the zone above the combination, is relieved through the passage means into the zone, and whereby when the combination is put down in the well, while the Well is full of mud for controlling the bottom pressure of the well, the mud can pass upwardly through the combination into the zone, the combination acting as a float, so that damage to the combination from upward pressure in the well is avoided.

A still further object of the invention is the provision of combination circulation stops and swabs which are devised for single tubing and multiple tubing operations, and which are effective for the purposes of the present invention, without a packer below the device, where the well is a pumping well, and substantial well bottom pressure does not exist.

Other important objects and advantageous features of the invention will be apparent from the following description and the accompanying drawings, wherein, for purposes of illustration only, a specific form of the invention is set forth in detail.

In the drawings:

FIGURE 1 is a vertically contracted schematic view showing combination circulation stop and swab means of the invention installed in the casing of an oil well, with the heating means at ground level;

FIGURE 2 is an enlarged horizontal section taken on the line 22 of FIGURE 1;

FIGURE 3 is a further enlarged and fragmentary vertical section taken on the line 33 of FIGURE 2, showing the valve means in closed position in full lines and in open position in phantom lines;

FIGURE 3 is a view similar to FIGURE 3, showing a solid unvalved device;

FIGURE 4 is a horizontal section, on a reduced scale, taken on the line 44 of FIGURE 3;

FIGURES 5, 6 and 7, are horizontal sections taken on the lines 55, 6-6, and 77, respectively, of FIG- URE 3;

FIGURE 8 is an enlarged horizontal section taken on the line 88 of FIGURE 9, showing a combination circulation stop and swab accommodating a plurality of tubings;

FIGURE 9 is a side elevation, partly broken away and in section, showing the combination of FIGURE 8; and

FIGURE 10 is a fragmentary vertical transverse section taken on the line 10-10 of FIGURE 8.

Referring in detail to the drawings, wherein like numerals designate like parts'throughout the several views, the numeral 10 generally designates a conventional oil well casing, fixed in a well bore 12, and having a head 14 rising above the ground level G, the head 14 having a cap 16, through which rises, as indicated at 18, the upper end of a tubing which extends downwardly and concentrically in the casing 10. The tubing 20 is connected, as generally indicated at 19, to suitable tanks 21. The tubing 20 has a packer 17 thereon, in the case of a flowing well.

A suitable circulating fluid heater 22 is supported on the ground G, alongside of the well head 14, as on a skid 24, on which it is brought to the well, and includes a tank 26 whose fluid capacity is at least one-half again the capacity of the fluid capacity of the annulus 27 of the well between the tubing 20 and the well casing 10 above a combination circulation stop and swab present in the casing. Operation of a burner 28 for the tank 26 is controlled by a thermostat 29 in accordance with the temperature of the fluid in the tank so as to assure that the temperature of the heating fluid circulated in the annulus 27 is above the melting temperature of paraflin in the tubing. Mounted on the skid 24 is a suitable force and circulating pump 30 having an intake conduit 32 leading thereto from the tank 26, and a discharge conduit 34, leading from the pump to a down pipe 36 having a downwardly opening check valve 37 in its open lower end. A fluid return pipe 37 leads from the well casing head 14 to the tank 26. On the top of the tank 26 is a burner stack 31, and a plurality of filtered gas pressure outlets 33 through which any gas present in the fluid in the tank can escape without producing fire danger. Appropriate safety valves (not shown) are provided in the conduits 32 and 34. Suitable circulating fluid sampling means (not shown) can be used to sample the fluid in the tank 26, so as to determine the condition of the well, including the condition of a packer, in the case of a flowing well, in the manner of a snitch box, or tattle tale.

The down pipe or heating fluid circulatory pipe 36 is of substantially smaller diameter than the well tubing 20 and extends downwardly along the tubing and has an open lower end 38 which is located near to and spaced above the combination circulation stop and swab present in the well casing 10, at a predetermined selected level below the well head 14. The down pipe 36 is fixedly secured to a side of the tubing 20 by means of easily installed clamps 40, located at vertically spaced points therealong. As shown in FIGURES 2 and 3, the clamps 40 comprise continuous flat metal bands which have opposed arcuate portions 42, to conformably engage opposite sides of the tubing 20, and a single substantially two-thirds circular portion 44 of smaller diameter between the arcuate portions 42 to conformably embrace the down pipe 36, the arcuate portions 42 having opposed and spaced ears 46 on their free ends, through which a clamping bolt 48 is engaged. The down pipe 36 is suitably connected, at its upper end, to the pump discharge conduit 34, as indicated at 50.

A combination circulation stop and swab, generally designated 52, is threaded on the lower end of an upper section 54 of the tubing 20, as shown in FIGURE 3, the combination being adapted to serve as a circulating stop and as a swab when withdrawn from the well, for forcing the circulating fluid out of the well. As shown in FIGURE 1, two such combinations 52 can be used, one above the other, where desired, the lower combination in such an installation being connected to the upper combination by a short tubing section 56, and to the upper end of a lower tubing section 58.

The combination 52 comprises a central tube 60 having internally threaded upper and lower ends 62 and 64 to thread onto the lower end of upper tubing section 54 and the upper end of the short or intermediate tubing section 56. Surrounding, and fixed relative to the central tube 60 is a cylindrical sleeve 66 which is substantially larger in diameter than the tube '60 and substantially smaller in diameter than the well casing 10, so that the sleeve 66 is concentrically spaced from the sidewall 68 of the well casing 10 at a distance preferably greater than half the distance between the tubing 20 and the casing sidewall.

The sleeve 66 has an external annular stop flange or ring 70 at its lower end 72, which has an outwardly and upwardly bevelled bottom surface 74 and a flat horizontal top surface 76 which is indented at the peripheral surface 78 of the sleeve 66, to provide an annular anchoring groove 80. An upwardly flaring annular sealing head 82 of such as hard rubber or other suitable solid nonmetallic heat-resistant material of limited resilience and compressibility, has an axial bore 84 therethrough which securably receives the sleeve 66, with its smaller lower end 86 bearing upon the top surface 76 of the stop ring 70 and having a downwardly extending annular anchoring rib 88 conformably engaged in the anchoring groove 80. The upper and larger end 90 of the head 82 is radially outwardly and upwardly curved, relative to, and extends slightly above the upper end 92 of the sleeve 66, the upper end 92 being bevelled to merge into the upper end 90 of the head 82.

An annular concave retaining plate 94 overlies and is contoured to bear downwardly and conformably upon the upper end 90 of the head 82 and upon the upper end 92 of the sleeve 66. The inner edge 96 of the plate 94 is flush with the side wall 98 of a concentric circular recess 100 in the upper end of the sleeve 66 and the outer edge 102 of the plate is spaced radially inwardly of the cylindrical peripheral surface 104 of the head 82, and is engaged with the inward edge 106 of an upstanding annular bead 108 on the head. The peripheral surface 104 bears conformably and sealingly against the well casing sidewall 68. The retaining plate 94 is preferably of non-corrosive alloy metal and is bonded to the upper end of the head 82. A steel protective ring 110 is fixed upon the plate 94, at its inner edge. The upper end of the central tube 66 extends above the bottom 112 of the recess and above the protective ring 110.

The sleeve 66 comprises a cylindrical sidewall 114 to which the head 82 is secured, the sidewall 114 being concentrically spaced around the central tube 60, and rigidly connected thereto by means of diametrically opposed and equally spaced radial relatively narrow struts 116 and 117, the struts 117 being thicker than the struts 116, whereby an equal number of vertically and circumferentially elongated, arcuate fluid passages 118 are defined, which open, at their upper ends to the recess 100, and hence through the upper end of the tool device 52, around and close to the upper tubing section 54, and substantially in vertical alignment with the open lower end 38 of the down pipe 36.

The two diametrically opposed struts 117 have lower ends 120 which are spaced upwardly from the lower end of the tube 60 and the sleeve 66 and have formed therein parallel upwardly extending blind bores 122. Below the lower ends 120 the inner surface of the sleeve sidewall 114 is arcuately and annularly recessed, as indicated at 124, to provide free upward circulation of fluid around an annular valve 126.

The valve 126 comprises an annular wedge-shaped body 128, of such as hard rubber, to which upstanding pins 130 are fixed, which work loosely in the blind bores 122 and have helical springs 132 circumposed thereon and compressed between the valve body 128 and the lower ends 120 of the struts 117, whereby the valve 126 is biased downwardly, as indicated in phantom lines in FIGURE 3, to normally close an annular valve seat 134. The valve body 128 has inner and outer compressible sealing rings 136 and 138, set in inner and outer grooves 140 and 142, respectively, provided in the sides of the body 128 near its top surface 144, for sealingly engaging the seat 134.

The valve seat 134 comprises radially spaced inner and outer sidewalls 146 and 148, which engage the inner and outer surfaces of an annular opening 154 formed in the lower end 72 of the sleeve 66 and communicating with the passage 118, the seat 134 being held up in place by a snap ring 156 removably seated in a retaining groove 158 provided in the outer surface of the annular opening 154. Inner and outer sealing rings 160 and 162 are seated in grooves 164 and 166, in upper parts of the sidewalls of the seat 134. The seat 134 walls have inwardly bevelled upper edges 168 and 170, with which the valve 126 engages, in its depressed position. At equally spaced intervals around the valve 126 webs 172 extend between the lower edges of the sidewalls 146 and 148 of the seat, as shown in FIGURE 7, here shown as being three in number, so as to define three circumferentially elongated arcuate ports 174. The webs 172 have V-shaped upper surfaces 174 which are conformably engaged by the valve 126 in the depressed portion of the valve, wherein the valve closes the ports 174.

In operation, fluid heated in the heater tank 26 is forced downwardly through the down pipe 36 by operation of the pump 30 and around the tubing 20, fills the zone within the casing above the combination 52, and warms the tubing so as to melt off deposited paraflin and prevent the further deposition of paraflin thereon. The above described circulation of the fluid heater in the tank raises the temperature of the down pipe 36, the tubing 20, and the well casing 10, as Well as that of the combination 52, so that any paraffin present on the sidewall of the tubing and any paraflin particles present in the well fluid, are melted and flow freely out of the well into the tanks 21.

For use in pumping wells wherein well bottom pressure is substantially absent, the combination circulation stops and swabs do not require relief passages therethrough, but, instead, are made solid and imperforate as shown in FIGURE 3 FIGURES 8 to 10 show a combination circulation stop and swab, generally designated 52 for use with multiple tubings The body of the device 53 is solid except for the necessary number of vertical bores to the ends of which the tubing sections are threadably connected, and a single eccentric valved passage 118 having a normally closed downwardly spring pressed valve 126 therein. A down pipe 36 is shown as secured along one of the tubing-s 20 Although there have been shown and described herein preferred forms of the invention, it is to be understood that the invention is not necessarily confined thereto, and that any change or changes in the structures of and in the relative arrangements of components thereof are contemplated as being within the scope of the invention as defined by the claims appended hereto.

What is claimed is:

1. A system for controlling paraflin in the tubing of an oil well having a casing, said system comprising a combination circulation stop and swab surrounding the tubing and positioned at a level below the head of the well so as to define a circulation zone above the combination in the space between the tubing and the casing,

said combination occupying the annulus between the tubing and the well casing and serving to isolate said zone from the annulus below said combination, a circulation tank, a pump connected to said tank and having a discharge leading into said zone and an intake leading from the upper part of said zone into the tank, said combination being out of communication with the tubing, said discharge being a down pipe extending downwardly along and secured to the tubing in the space between the tubing and the casing and having an open lower end near to and spaced upwardly from said combination, and a downwardly opening check valve in said open lower end.

2. A system for controlling paraflin in the tubing of an oil well having a casing, said system comprising a combination circulation stop and swab surrounding the tubing and positioned at a level below the head of the well so as to define a circulation zone above the combination in the space between the tubing and the casing, said combination occupying the annulus between the tubing and the well casing and serving to isolate said zone from the annulus below said combination, a circulation tank, a pump connected to said tank and having a discharge leading into said zone and an intake leading from the upper part of said zone into the tank, said combination being out of communication with the tubing, said discharge being a down pipe extending along and in heat transfer contact with the tubing, said down pipe being imperforate and having an open lower end located above and near to said combination.

3. In combination, a well bore extending downwardly from ground surface, a well casing engaged in said bore, said casing having a head extending above ground surface, a well tubing extending through said head and downwardly in the well casing and being concentrically spaced from the sidewall of the casing, a down pipe secured to and in heat transfer contact with the tubing and extending downwardly therealong in the space between the tubing and the casing, said down pipe having an open lower end, combination circulation stop and swab means surrounding and secured to the tubing at a location spaced below and near to the lower end of the down pipe and locking the annulus between the tubing and the well casing sidewall, an assembly comprising a fluid heating tank and a pump having an intake connected to the tank and a discharge connected to the down pipe, and a fluid return pipe leading from the casing head into the tank.

4. In combination, a well bore extending downwardly from ground surface, a well casing engaged in said bore, said casing having a head extending above ground surface, a well tubing extending through said head and downwardly in the well casing and being concentrically spaced from the sidewall of the casing, a down pipe secured to and in heat transfer contact with the tubing and extending downwardly therealong in the space between the tubing and the casing, said down pipe having an open lower end, combination circulation and swab means surrounding and secured to the tubing at a location spaced below and near to the lower end of the down pipe and blocking the annulus of the well between the tubing and the well casing sidewall, an assembly comprising a fluid heating tank and a pump having an intake connected to the tank and a discharge connected to the down pipe, and a fluid return pipe leading from the casing head into the tank, said combination means comprising at least two combination means located at vertically spaced point-s.

5. A system for controlling parafiin in the tubing of an oil well having a casing spacedly surrounding the tubing, said system comprising a combination stop and swab fixed to and surrounding the tubing at a level below the head of the Well and blocking the space between the tubing and the casing at that level, said combination having vertical passage means extending therethrough, upwardly opening check valve means in said passage means, means at the head of the well for circulating heat-ing fluid under pressure downwardly in the space between the tubing and 7 S the casing and recovering the heating fluid from said space 2,614,635 10/52 Williams et a1; 166-40 at a point adjacent the well head, said circulating means 2,705,535 4/55 Waterman 16640 comprising an imperforate down pipe extending down- 2,914,124 11/59 Ripley 16640 wardly in said space in heat transfer contact with the 2,918,880 12/59 Jones 103225 tubing, said down pipe having an open lower end spaced 5 2,972,379 2/61 Brown 166202 above and near to said combination. 2,975,722 3/61 Webber 103225 References Cited by the Examiner BENJAMIN HERSH, Primary Examiner.

UNITED STATES PATENTS BENJAMIN BENDETT, CHARLES E. OCONNELL,

- 1,520,012 12/24 Conrader 166-40 Examiners- 1,888,125 11/32 Hart 166202 

1. A SYSTEM FOR CONTROLLING PARAFFIN IN THE TUBING OF AN OIL WELL HAVING A CASING, SAID SYSTEM COMPRISING A COMBINATION CIRCULATION STOP AND SWAB SURROUNDING THE TUBING AND POSITIONED AT A LEVEL BELOW THE HEAD OF THE WELL SO AS TO DEFINE A CIRCULATION ZONE ABOVE THE COMBINATION IN THE SPACE BETWEEN THE TUBING AND THE CASING, SAID COMBINATION OCCUPYING THE ANNULUS BETWEEN THE TUBING AND THE WELL CASING AND SERVING TO ISOLATE SAID ZONE FROM THE ANNULUS BELOW SAID COMBINATION, A CIRCULATION TANK, A PUMP CONNECTED TO SAID TANK AND HAVING A DISCHARGE LEADING INTO SAID ZONE AND AN INTAKE LEADING FROM THE UPPER PART OF SAID ZONE INTO THE TANK, SAID COMBINATION BEING OUT OF COMMUNICATION WITH THE TUBING, SAID DISCHARGE BEING A DOWN PIPE EXTENDING DOWNWARDLY ALONG AND SECURED TO THE TUBING IN THE SPACE BETWEEN THE TUBING AND THE CASING AND HAVING AN OPEN LOWER END NEAR TO AND SPACED UPWARDLY FROM SAID COMBINATION, AND A DOWNWARDLY OPENING CHECK VALVE IN SAID OPEN LOWER END. 